Add healthcheck endpoint, spec testing

Gemfile

@@ -6,7 +6,7 @@ gem 'puma', '~> 4.3'
 gem 'rack', '~> 2.2'
 gem 'rake', '~> 13.0'
 gem 'redis', '~> 4.1'
-gem 'rbvmomi', '~> 2.1'
+gem 'rbvmomi', '~> 2.4', '>= 2.4.1'
 gem 'sinatra', '~> 2.0'
 gem 'prometheus-client', '~> 2.0'
 gem 'net-ldap', '~> 0.16'

lib/vmpooler/api.rb

@@ -3,7 +3,7 @@
 module Vmpooler
   class API < Sinatra::Base
     # Load API components
-    %w[helpers dashboard reroute v1 request_logger].each do |lib|
+    %w[helpers dashboard reroute v1 request_logger healthcheck].each do |lib|
       require "vmpooler/api/#{lib}"
     end
     # Load dashboard components
@@ -40,6 +40,10 @@ module Vmpooler
         require 'prometheus/middleware/exporter'
         use Vmpooler::Metrics::Promstats::CollectorMiddleware, metrics_prefix: "#{metrics.prometheus_prefix}_http"
         use Prometheus::Middleware::Exporter, path: metrics.prometheus_endpoint
+        # Note that a user may want to use this check without prometheus
+        # However, prometheus setup includes the web server which is required for this check
+        # At this time prometheus is a requirement of using the health check on manager
+        use Vmpooler::API::Healthcheck
       end
 
       if torun.include? :api

lib/vmpooler/api/healthcheck.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+module Vmpooler
+  class API
+    class Healthcheck < Sinatra::Base
+      get '/healthcheck/?' do
+        content_type :json
+
+        status 200
+        JSON.pretty_generate({ 'ok' => true })
+      end
+    end
+  end
+end

spec/integration/api/healthcheck_spec.rb

@@ -0,0 +1,56 @@
+require 'spec_helper'
+require 'rack/test'
+
+describe Vmpooler::API::Healthcheck do
+  include Rack::Test::Methods
+
+  def app()
+    Vmpooler::API
+  end
+
+  # Added to ensure no leakage in rack state from previous tests.
+  # Removes all routes, filters, middleware and extension hooks from the current class
+  # https://rubydoc.info/gems/sinatra/Sinatra/Base#reset!-class_method
+  before(:each) do
+    app.reset!
+  end
+
+  let(:config) {
+    {
+        config: {
+            'site_name' => 'test pooler',
+            'vm_lifetime_auth' => 2,
+        },
+        pools: [
+                    {'name' => 'pool1', 'size' => 5, 'alias' => ['poolone', 'poolun']},
+                    {'name' => 'pool2', 'size' => 10},
+                    {'name' => 'pool3', 'size' => 10, 'alias' => 'NotArray'}
+                ]
+    }
+  }
+
+  let(:current_time) { Time.now }
+
+  let(:metrics) {
+    double("metrics")
+  }
+
+  before(:each) do
+    expect(app).to receive(:run!).once
+    expect(metrics).to receive(:setup_prometheus_metrics)
+    expect(metrics).to receive(:prometheus_prefix)
+    expect(metrics).to receive(:prometheus_endpoint)
+    app.execute([:api], config, redis, metrics, nil)
+    app.settings.set :config, auth: false
+  end
+
+  describe '/healthcheck' do
+    it 'returns OK' do
+      get "/healthcheck"
+      expect(last_response.header['Content-Type']).to eq('application/json')
+      expect(last_response.status).to eq(200)
+      result = JSON.parse(last_response.body)
+      expect(result).to eq({'ok' => true})
+    end
+  end
+end